Aeronautical propeller



P. THOMSON AND M. J. WHELAN.

AERONAUTICAL PROPELLER. APPLICATION FILED DEC. 15. 1917.

1 4111 9 18% Patented June 13, 192.2.

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PROCTER THOMSON AND MICHAEL J. WHELAN, OF MUSKEGON', MICHIGAN, ASSIGNORSTO THE BRUNSWICK-BALKE-COLLEND CORPORATION OF DELAWARE.

ER COMPANY, OF CHICAGO, ILLINOIS, A

AERONAU'IICAL PROPELLER.

ntense.

Specification of Letters Patent. Patented June 13, 1922.

Application filed. December 15, 1917. Serial No. 207,282.

To all whom it may concern:

Be it known that we, PROCTER THOMSON and MICHAEL J. WHELAN, citizens ofthe United States, residing at Muskegon, in the county of Muskegon andState of Michigan,

have invented certain new and useful Improvements in AeronauticalPropellers, of which the following is a specification.

This invention relates to aeronautical projpellers and has for itsobject the elimination of the inherent disadvantages resulting from thecommon mode of constructing propellers and the provision of a propellerof the requisite strength, rigidity and lightness which presents asmooth, indurated, weatherproof surface. l

Further objects and advantages of our invention will be betterunderstood by reference to the following specification when read inconnection with the accompanying illustrating the preferred embodimentthereof, in which Fig. 1 is a side elevation of an aeronauticalpropeller of the well known form and construction Fig. 2 is a sideelevation of a propeller according to our invention;

Fig. 3 is an enlarged sectional view of the structure illustrated inFig. 2, and

Fig. 4 is an enlarged sectional view through the hub of the propeller.

Aeronautical propellers have heretofore been constructed by superposi'nga plurality of layers or laminations of some suitable hard wood, thelayers being secured together by an adhesive such as glue. From theblock thus formed the propeller is shaped. Even when the utmost care isexercised in building up the blocks a large proportion of the propellerswill be rejected because of imperfect joining of the layers whichbecomes apparent only after the propeller is partially or wholly shaped.A large amount of material and labor is thus wasted. Moreover propellersapparently perfect when finished frequently develop flaws after beingused for a short time. These flaws permit the air to enter between thelayers of temperature and humidity to which propellers are subjected inuse sooner or later afi'ect the wood and glue and increases theliability of wood propellers to fail. Finally the constant friction ofthe air on wood propellers quickly wears the surfaces to an extent whichruins them after a short interval of use.

,We propose to overcome these and other inherent defects of woodpropellers by pro viding a core and enclosing the same 1n a hard, dense,impervious shell of a suitable weather proof material which isintegrally united with the core. We have found that hard rubber is avery desirable material for this purpose because it can be vulcanized tothe core and integrally united therewith,

propeller is reduced to a minimum, thereby saving material and laborwhich more than offsets the slightly increased cost of our construction.A safer and' more dependable propeller is thus provided.

Referring to the drawing, we have illustrated in Fig. 1 for purpose ofcomparison a common wood propeller made up of a plurality of layers 5 ofwood joined by means of glue.

In Figs. 2, 3 and 4 we have illustrated our propeller which consists ofa core made up of a plurality of layers 6 of wood secured together bymeans of glue and shaped to approximately the finished form of thepropeller. The surface of the wood is preferably left rough, thuseliminating the necessity and expense of finishing, and also permittinga better bond between the wood and hard rubber shell 7.

The shell is applied by arranging a layer of uncured rubber compositionabout the core which is then disposed in a suitable mold of the shapeand contour of the finished propeller.- By subjecting the mold topressure and heat in the well understood manner the rubber is vulcanizedand inte rally united with the core. Upon remove from the mold at thecompletion of the vulcanizing operation the propeller may be polishedand it is then ready for immediate use.

From the foregoing it will be readily understood that we have perfectedan aeronautical propeller which presents numerous advantages over woodpropellers and that various changes may be made in the shape, dimensionsand relative thickness of the core and shell Without departing from thespirit and scope of the invention or sacrificing any of the advantagesof the invention, the form hereinbefore described being merely thepreferred embodiment thereof. While we now prefer to use hard rubber toPROCTOR THOMSON. MICHAEL J. WHELAN.

Witnesses J. O. MATTESON, D. VA K, Jr.

